var m=6; //�����ʾͼƬ�������� 
var n=Math.floor(Math.random()*m+1) 
switch(n) 
{ 
case 1: 
document.write('<img border=0 src="/doublechoice/images/m1.gif";></a>'); 
break; 
case 2: 
document.write('<img border=0 src="/doublechoice/images/m2.gif";></a>'); 
break; 
case 3: 
document.write('<img border=0 src="/doublechoice/images/m3.gif";></a>'); 
break; 
case 4: 
document.write('<img border=0 src="/doublechoice/images/m4.gif";></a>'); 
break; 
case 5: 
document.write('<img border=0 src="/doublechoice/images/m5.gif";></a>'); 
break; 
case 6: 
document.write('<img border=0 src="/doublechoice/images/m6.gif";></a>');
break; 
} 
